[Freeciv-Dev] Re: (PR#7279) Macro optimizations

["Raimar Falke" <i-freeciv-lists@xxxxxxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=7279 >

On Wed, Jan 21, 2004 at 09:24:46AM -0800, Arnstein Lindgard wrote:
> > Use of alloca() to create temporary stack space is a potential
> > compatibility issue, but can be removed by making preallocation
> > of local storage in env a requirement or part of the definition
> > macro rather than option.

> Assuming we need local variables:
> 
> My linux man pages says alloca() is non POSIX and it's use is
> discouraged. Some existing Freeciv code (which looks imported)
> substitutes alloca() with malloc() if you don't have a requirement,
> and that introduces overhead for one function call in your macro.

Indeed. alloca is forbidden in freeciv. Note that C99 provides a
portable replacement: variable sized arrays. So 

int f(int n)
{
  char *p=alloca(n);

becomes

int f(int n)
{
  char p[n];

But I have the feeling that this doesn't help here.

> bool normalize_map_pos(int *x, int *y)    would become
> normalize_map_pos(ENV, X, Y)

I'm sure that this won't happen.

        Raimar

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